The video begins with an application of eye cream on the under eye bags, and then the timer begins. As the cream dries –- sometimes with the help of a fan or waving a hand under the eye –- the bags seem to disappear completely.

Dermatologist Whitney Bowe appeared on “GMA” on Wednesday to perform a live demonstration of one such cream. She applied it to a “GMA” viewer while the clock ticked to see how long the cream took to achieve its effect.

While she waited for the cream to act, she explained how under eye bags develop.

"As we age, the fat pads under the eye, it actually herniates," Bowe said. "So basically, the internal lift structures that normally hold those fat pads in place, they get looser and then they bulge out and that's what people see as an under eye bag. It just makes you look tired."

Bowe also explained how under eye creams worked. The molecules in the eye cream bind tightly to the skin as they dry, creating a smoother-looking surface, she said. The creams are like Spanx for the eyes, she noted.

"It only lasts a couple of hours," she said. "It's not long term, but hey, it sure looks good for now."

Bowe said the eye cream's effect derived from ingredients including silicates and glycerin. Other ingredients to look for in under eye bag creams include caffeine -– which constricts blood vessels – and hyaluronic acid, which plumps wrinkles by hydrating them beneath the surface of the skin. Antioxidants such as vitamin E and peptides, which thicken the skin, are also important ingredients in creams, Bowe said.